Molecular dynamics simulation of CL20/4-bromo-3,5-dinitro-1-methylpyrazole (BMDNP) eutectic-based PBXs

CL-20/BMDNP eutectic explosive is a late-model explosive with excellent energy density and detonation parameters, but it still has higher sensitivity than TATB and FOX-7. In an attempt to reduce the sensitivity of CL-20/BMDNP eutectic explosive, a CL20/BMDNP eutectic model was installed in the paper. Polymer-bonded explosives (PBXs) were obtained by adding five different types of polymers, such as butadiene rubber (BR), ethylene-vinyl acetate copolymer (EVA), polyethylene glycol (PEG), fluoropolymer (F₂₆₀₃), and polyvinylidene difluoride (PVDF), to six cleavage surfaces(1 0 0), (0 0 1),(0 1 1),(0 -1 1), (1 1 0), and (1 -1 0), respectively. The sways of various polymers on the stability, trigger bond length, mechanical properties, and detonation properties of PBXs were predicted. The CL-20/BMDNP/PEG model has maximum binding energy and minimum trigger bond length among the five PBX models, manifesting that the CL-20/BMDNP/PEG model has tip-top stability, compatibility, and lowest sensitivity. Besides, despite the CL-20/BMDNP/F₂₆₀₃ model exhibiting exceptional detonation competences, it is supposed to denote that this model revealed a low level of compatibility. In conclusion, the CL-20/BMDNP/PEG model showed better integrated capacities, indicating that PEG is a more appropriate binder choice for PBXs on the basis of the CL-20/BMDNP cocrystal.

The molecular dynamics (MD) simulation method was used to investigate the properties of CL-20/BMDNP eutectic and its PBXs composites. All simulations were performed in the Materials Studio software platform. The COMPASS force field suitable for energetic materials was selected in the simulation process. The system was first equilibrated under the Isothermal-isobaric (NPT) ensemble at 295 K; the simulation duration was 2 ns, and the integration step was 1 fs.